This midline bifrontal transbasal approach has been mostly used for the extradural tumor of the middle anterior skull base. An olfactory nerve is preserved in the unilateral transbasal approach, but olfaction is generally sacrificed when the bifrontal transbasal approach is used. In the extensive transbasal approach, the bifrontal craniotomy is combined with a supraorbital osteotomy to allow the surgeon to perform an ethmoidectomy, sphenoidostomy, and extensive clivectomy. This approach affords the surgeon access to the cavernous sinus and the orbital apex. The surgical angle makes control of hemorrhage from the medial cavernous sinus challenging. Although an extensive intradural exposure is possible, it is generally avoided because of the risk of postoperative infection. The approach is most often used for the resection of midline clival lesions, frontal skull base lesions, medial orbital lesions, and paranasal lesions, including nasopharyngeal tumors, chondrosarcomas, chordomas, and meningiomas.

Key Steps

Position: Supine

Step 1. Reflection of scalp (Fig. 4.1)

Step 2. C raniotomy (Fig. 4.10

Step 3. Closure of the anterior fossa dura (Fig. 4.18)

Step 4. Osteotomy of orbital roots (Fig. 4.21

Step 5. Ethmoidectomy (Fig. 4.30)

Step 6. Sphenoidostomy (Fig. 4.39)

Step 7. Clivectomy (Fig. 4.49)

Step 8. Intradural exposure (Fig. 4.53)

Variations of the Transbasal Approach

1. 
   

   Unilateral transbasal approach

   
   
2. 
   

   Standard bifrontal transbasal approach

   
   

   without removal of the supraorbital bar

   
   
3. 
   

   Limited bifrontal transbasal approach

   
   

   removal of the supraorbital bar

   
   

   between supraorbital foramen or notch

   
   
4. 
   

   Extended bifrontal transbasal approach

   
   

   removal of the whole supraorbital bar

   
   
5. 
   

   Extensive bifrontal transbasal approach

   
   

   removal of the whole supraorbital bar and lateral orbital wall

Illustrated Steps with Commentary